The present invention relates to a speech signal compression device, a speech signal compression technique and a program.
Recently, a speech synthesis method for converting text data and the like to speech has been used in the field of car navigation, for example.
In speech synthesis, for example, words, basic blocks and modification relations among the basic blocks included in text data are identified, and the way of reading the sentence is identified based on the identified words, basic blocks and modification relations. Then, the waveform, the duration and the pitch (fundamental frequency) pattern of phonemes to constitute speech are determined based on the phonogram sequence indicating the identified way of reading. Then, the waveform of speech indicating the entire sentence including kanjis and kanas is determined based on the result of the determination, and speech with the determined waveform is outputted.
In the above-mentioned speech synthesis method, in order to identify a speech waveform, a speech dictionary is searched in which speech data indicating waveforms or spectral distribution of speeches have been accumulated. The speech dictionary is required to have a great number of speech data accumulated therein in order to make synthesized speech natural.
In addition, when this method is applied to a device required to be downsized, such as a car navigation device, it is generally necessary to downsize a storage device for storing a speech dictionary to be used by the device. When the size of the storage device is decreased, decrease of the storage capacity is generally unavoidable.
Accordingly, in order to enable a speech dictionary with a sufficient amount of speech data included therein to be stored in a storage device with a small storage capacity, data compression of speech data has been used to reduce the data capacity of one speech datum (see National Publication of International Patent Application No. 2000-502539, for example).